We have recently put some old tape changer in the public area for group use.


System Drive Tape Device Changer Device Capacity Notes
tripoli ADIC 22 DLT4000 /dev/rmt/0 /dev/scsi/changer/c1t1d0 22x 20/40 GB Used to be used for roma's backups
cancun ADIC 22 DLT4000 /dev/rmt/0 /dev/scsi/changer/c1t1d0 22x 20/40 GB Used to be used for rio's backups

Tape Changer

To control the tape changer we have two programs installed:

  • MTX - a fairly low-level program for changing tapes, it's also fairly powerful.
  • tapechanger - uses TapeChanger::MTX to control the tape drive in a pretty reasonable manner (it was designed for backup use). For more information, 'man tapechanger' or 'man TapeChanger::MTX' on a Sun.

Writing to Tapes

You will probably want to write to tape with either dd, ufsdump, or gtar. I'm not (at this point) going to write out a tutorial on these commands or using them with tapes; just read the man pages (carefully!) and make sure you label your tapes properly.

Choosing which device node to use is more effort than just typing in '/dev/rmt/0'. Different flags at the end of the device name ('/dev/rmt/0n', for instance) offer different behaviours; you'll probably want to use these sometimes. Our backups have generally used '/dev/rmt/0cbn' or equivalent.

Letter Meaning Implication
n Don't rewind the tape after using it Can put multiple volumes per tape.
c Compress the data to the tape  
b BSD behaviour More-readable by a variety of OS's.

More information can be found on the mtio web page.

Getting Tapes

We currently have ~200 DLT4000 tapes left over from when we used regular DLT tapes for backups. Each one will store 20GB uncompressed, or (nominally) 40GB compressed, when used on the public drives. I will give them out to users as necessary, but I must personally approve the use of each tape! I don't want you accidently taking the wrong tapes or taking one from the wrong pile...